tong1 ze3 bu2 tong4, tong4 ze3 bu4 tong1.
Literally it means: If it isn't blocked, then it doesn't hurt; if it hurts, then it's blocked.
This clever play of Chinese homophones contains the essence of traditional Chinese medicine.
According to the TCM, our body energy ( Chi' and blood) is carried through a special web of channels called meridians. If these pathways of energy are free of blockage, we are healthy without any discomforts or pain. However, if certain parts of the pathways are blocked, the whole circulation is disrupted. As a result, we feel pain somewhere.
As is shown in Chinese characters, the difference between congestion (不通) and pain (痛) is not that big. Once you clear up the congestion, the pain will disappear.
But how would you get rid of the congestions in your meridians? Here is another Chinese proverb about pain.
tou2 tong4 yi1 tou2, jiao3 tong4 yi1 jiao3.
It literally means: Treat the head if you've got a headache; treat the feet if your feet hurt.
This is a description of bad doctors according TCM standards. Pain is only a symptom rather than the cause of the problem. A TCM master will try to relate all the other physical indications (including the color of your tongue, your pulse, bowel movement, etc) to figure out the cause of the pain. Therefore, an experienced doctor will probably treat your head when your feet hurt, or treat your feet when your head hurts.